The present invention relates to the sterilization arts. It finds particular application in connection with a sliding sterilizer door for sealing the opening to a sterilization chamber, and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to a variety of doors which are subject to thermal and mechanical stresses during their operation.
Steam sterilizers generally operate over a range of internal temperatures and pressures. The temperature and pressure within the sterilizer are varied as the sterilization cycle progresses. To withstand the fluctuating pressures, sterilizer doors are generally constructed from a solid metal plate. For additional strength, a supporting structure may be welded to an exterior surface of the plate.
For economic reasons, it is desirable for the door plate and the supporting structure to be formed from different materials. The doorplate is generally formed from a material which is both relatively strong and resistant to the chemical conditions of the sterilizer, such as stainless steel. The supporting structure may be formed from a material chosen solely for its strength as it need not be resistant to chemical degradation. The different materials used for the plate and the supporting structure frequently have different coefficients of expansion.
The temperature gradients in the sterilizer cause thermo-mechanical stresses to develop in the door. When heated, the different materials of the door expand to different extents. For larger doors, such as those used in walk-in steam sterilizers, such relative expansions are magnified, and tend to cause distortion of the door. The thermal distortion can hinder door operation during opening and closing and lower the service life of the door through fatigue of the materials.
One way to overcome the problem in larger doors is to use similar materials for both the door plate and supporting structure. However, this prevents use of the most economical mix of materials for construction of the door.
The present invention provides for a new and improved sterilizer door which overcomes the above-referenced problems and others.